Conventionally, an electric vehicle charges its battery, which is used as a power source for driving the vehicle, at a charge station (i.e., a charge point). Japanese Patent Laid-Open No. 2003-262525 (JP '525) and Japanese Patent Laid-Open No. 2011-252816 (JP '816) disclose a technique to provide information of charge stations around a current position of the vehicle.
Further, Japanese Patent Laid-Open No. 2000-46571 (JP '571) discloses a technique that calculates a travel distance of the vehicle based upon the remaining energy of the battery (i.e., a currently-reserved energy). Based on the travel distance calculated, JP '571 notifies the user (e.g., driver) of the need to charge the battery at a nearest energy supply facility (i.e., nearest charge station) when the travel distance calculated is shorter than a distance to a second nearest energy supply facility.
In JP '571, the technique disclosed notifies the user of the need to charge the battery when the vehicle is able to reach the nearest energy supply facility and is not able to reach the second nearest energy supply facility. In such the last moment notification scheme, the user is not allowed to visit, any other destination before charging at the nearest energy supply facility. In other words, the user's convenience and choice of routes and/or choice of destinations, are not considered in such notification technique.
Further, in view of a very few number of charge points and a low travel distance per charge (i.e. one full-charge), it is preferable to provide the notification regarding charging the battery at an earlier timing. However, in regards to an earlier notification, how and at what time such notification should be provided is still an issue. That is, for example, in a situation where an earlier notification is provided, which may lead to many charge stations reachable and selectable for charging, in what situation such an earlier notification is effectively provided to the user of the electric vehicle is difficult to determine.
For instance, even when it is necessary to have the earlier notification, the earlier notification may be an annoyance for the user and such notification may be wasted if provided in an inappropriate situation in which the user decides not to charge the battery.
Further, in a situation in which the use has many charge points all of which are reachable, a wrong notification prioritizing hard-to-reach charge points among the reachable charge points, burying easy-to-reach charge points under the hard-to-reach ones, may also be an annoyance and/or an inconvenience for the user of the electric vehicle.